﻿Two new species of Ismarus Haliday (Hymenoptera, Ismaridae) from Yunnan, China

﻿Abstract The genus Ismarus Haliday are rarely collected parasitoids in the small family Ismaridae. In this study, two new species are described from China’s Yunnan Province: Ismarusrobustus Chen & Yan, sp. nov. and Ismarusunisulcus Chen & Yan, sp. nov. An updated key to the Chinese species of the genus is provided.

The Chinese fauna of Ismarus has been extensively studied recently and nine species (Table 1) have been recorded (Liu et al. 2011;Kim et al. 2018b;Zhang et al. 2021). In this study, we describe another two new species from the mountainous region of Yunnan Province of southwest China.

Material and method
This work is based on the specimens collected by Malaise trap set in Gaoligongshan National Nature Reserve, Yunnan Province, China. All the studied specimens are deposited in the insect collection of the South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China (SCBG).
Specimens were examined using a Nikon SMZ800N microscope. Images and measurements were made using a Nikon SMZ25 microscope with a Nikon DS-Ri 2 digital camera system. Image plates were post-processed with Adobe Photoshop CS6 Extended. Mesoscutal suprahumeral sulcus present as six small pits (Fig. 1C); antenna entirely black (Fig. 2B)  Base of T2 with two costae forming a single furrow (Fig. 3E); A10-A15 black (Fig. 4B)  Diagnosis. This species can be easily distinguished from other Ismarus species by the following characters: largely black; mesoscutal suprahumeral sulcus present as six small pits; mesoscutellum with posterior rim excavate and slightly prominent posterolateral corners; hind tibia abruptly incrassate.

Taxonomy
Description. Female. Body length 3.33 mm. Colour. Body black; antenna entirely black; coxae, trochanters and basal femora of fore and mid legs dark, remainder brown to yellow, with tibia and tarsi becoming paler distally, hind leg mostly black with hind tibia laterally yellow-brown and hind tarsi pale yellow; wings hyaline, veins brown to black-brown.
Head. Head 2.0× as wide as long in dorsal view; vertex abruptly sloping behind ocelli in lateral view; POL as long as OOL; most of frons with scattered setae, except densely setose ventro-laterally; transverse facial carina convex ventrally; A3 as long as A4; A4 1.3× length of A5; A6-A14 with each segment approximately 1.4× longer than wide; A15 approximately 2.5× longer than wide.
Wings. Radial cell completely closed, moderately large, 5.0× as long as wide and 0.7× as long as marginal vein.
Legs. Fore and mid legs slender; hind tibia abruptly incrassate, its maximum width slightly wider than hind femur.
Male. Unknown. Etymology. Named after the comparatively robust body of this species. Distribution. China (Yunnan).     Diagnosis. This species is most similar to I. halidayi Förster but can be distinguished by the following characters: A4 slightly longer than A3 (A4 shorter than A3 in I. halidayi); median furrow of T2 very short, distinctly less than half the length of T2 (median furrow of T2 long, reaching half the length of T2 in I. halidayi); radial cell of fore wing 0.75× as long as marginal vein (radial cell as long as marginal vein in I. halidayi).
Description. Female. Body length 2.50-2.64 mm. Colour. Body black; A1-A9 brown to dark brown, remainder of antenna dark brown; fore and mid legs yellow-brown, with tarsi becoming darker distally, hind leg mostly dark brown with basal coxae somewhat dark and hind femur, trochanter and basal tibia yellow-brown; tegulae yellow-brown; wings hyaline, veins light brown to black-brown.
Head. Head 2.0× as wide as long in dorsal view; vertex abruptly sloping behind ocelli in lateral view; POL as long as OOL; most of frons with scattered setae, except densely setose ventro-laterally; transverse facial carina slightly convex ventrally; A4 slightly longer than A3; A4 1.5× length of A5; A6-A14 with each segment less than 1.5× as long as wide; A15 approximately 2.0× longer than wide.
Wings. Radial cell closed, moderately large, 5.6× as long as wide and 0.94× as long as marginal vein.
Legs. Fore and mid legs slender; hind tibia gradually swollen, its maximum width slightly wider than hind femur.
Metasoma. Petiole slightly shorter than wide (8:9), with strong costae dorsally; tergites smooth with scattered fine punctures; base of T2 with two short costae and a short median furrow, extending 0.37× length of T2; sutures between tergites complete and deeply impressed.
Male. Unknown. Etymology. The name refers to the single furrow present on the base of T2. Distribution. China (Yunnan).

Ethical statement
No ethical statement was reported.

Funding
This material is based upon work supported in part by the Insect Network of Sino-BON and the National Natural Science Foundation of China (32100360).

Author contributions
Conceptualization and methodology, all authors; resources, Yan-Qiong Peng; writingoriginal draft, Chengjin Yan and Hua-Yan Chen; writing-review and editing, all authors; supervision, Chengjin Yan and Hua-Yan Chen; funding acquisition, Chengjin Yan and Yan-Qiong Peng. All authors have read and agreed to the published version of the manuscript.